Remote desktop won't connect

Scenario: Two computers, same LAN, both Windows 7 Pro. We'll call them computers A and B. For a few years they could connect to each other using RDP. Now B can connect to A using Remote Desktop, but A cannot connect to B. In addition, there are four computers on a separate LAN, both LANs connected by VPN. In the past, any of the four could connect to B using Remote Desktop, but now none of them can. Any of those four can connect to A. I think this rules out the router. So what is wrong with system B?

I looked at the Windows Firewall rules on System B and it appears that all of the Inbound Rules for Remote Desktop are set to Allow. Even some "public" ones that make me nervous. (System B is a laptop that is occasionally used on the road.) Are there other rules I should look at?

I looked at services. All three of the Remote Desktop services are set to Manual, but were Started. (Should they be Manual or Automatic?)

I don't know what else to look at. It seems like some Microsoft Update came along and hosed something up, but I have no idea when it happened or which update it might have been. And that's just speculation, anyway.

Nevermind... Sometimes it is the simplest things that trip you up. The laptop had been out in the world so she switched the network to Public and IP address to DHCP, then forgot to switch it back again. We generally use static IP addresses for this very reason. I switched it back and all is well.